Loading Copy Sets an Expectation
SHOULD: Name the work and its expected duration inside a loading state ("Analyzing your data… this usually takes 30–60 seconds") instead of a bare "Loading…", which says the same thing at 1s and at 90s so the user cannot tell working from hung. Show a signal that advances, and give anything past ~10s an escape hatch.
Name the work being done and how long it usually takes, instead of shipping a bare "Loading…"
Bad
Good
Why it matters
The corpus already governs how a loading state looks — stable skeletons, matched dimensions, a minimum display duration — but nothing until now governed the words inside it, and the words are what carry the expectation. "Loading…" is a dead end: it says the same thing at one second and at ninety, so on a long job the user cannot distinguish "still working" from "hung", and the rational move becomes reloading the page and losing the work.
Name the work ("Importing 1,240 rows"), state the expected duration ("this usually takes about a minute"), and show a signal that advances. Anything past ten seconds also needs an escape hatch, because a bounded wait the user chose to abandon is far better than an unbounded one they had to guess about.